Startups are processing plant waste into concentrated carbon to be buried or injected underground. It’s like fossil fuels, but in reverse.
In a roundabout way, coal is solar-powered. Millions of years ago, swamp plants soaked up the sun’s energy, eating carbon dioxide in the process. They died, accumulated, and transformed over geologic time into energy-dense rock. This solar-powered fuel, of course, is far from renewable, unlike solar panels: Burning coal has returned that carbon to the atmosphere, driving rapid climate change.
But what if humans could reverse that process, creating their own version of coal from plant waste and burying it underground? That’s the idea behind a growing number of carbon projects: Using special heating chambers, engineers can transform agricultural and other waste biomass into solid, concentrated carbon. Like those ancient plants captured CO2 and then turned into coal, this is carbon naturally sequestered from the atmosphere, then locked away for (ideally) thousands of years.
To be abundantly clear: Such “carbon removal” techniques are in no way a substitute for reducing emissions and keeping that extra carbon out of the atmosphere in the first place. But at the annual COP28 conference last month, carbon removal was a hotter topic than ever before. For years, the Intergovernmental Panel on Climate Change has insisted that to keep warming below 1.5 degrees Celsius above pre-industrial temperatures, we’re going to need carbon removal in one form or another, preferably a bunch of techniques working in concert.
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